1. Field of the Invention
The present invention relates to a sensor node of a low power for a monitoring application in a mesh sensor network using a time division access scheme, and a routing method thereof. More particularly, the present invention relates to a sensor node that may decrease a power consumption and enhance a reliability using a routing function using a beacon, a neighboring node tracing function, and a beacon removal function, and a routing method thereof.
2. Description of the Related Art
Generally, a sensor node constituting a sensor network may operate by a battery. In order to maximize a battery lifetime, a battery consumption may need to decrease by lowering a duty cycle. One of schemes to lower the duty cycle may be a time division access scheme of allocating a time slot for each sensor node such as an Institute of Electrical and Electronics Engineers (IEEE) 802.15.4 standard. However, in the pure time division access scheme, the sensor node may need to be awakened every time slot of all the neighboring nodes in order to support a mesh. Therefore, a great amount of power may be consumed.
FIG. 1 illustrates a general operation example of a time division access Media Access Control (MAC) protocol.
Referring to FIG. 1, a network includes six sensor nodes, for example, a first sensor node A 101, a second sensor node B 103, a third sensor node C 105, a fourth sensor node D 107, a fifth sensor node E, and a sixth sensor node F. An arrow indicator 100 denotes a routing path. Here, the network indicates a monitoring application where all the packets gather in the third sensor node C 105. A single time slot may be allocated to each sensor node. Each sensor node may transmit and receive a beacon and data in the allocated time slot. Neighboring nodes may receive the beacon and data in the allocated time slot. For example, a time slot (1) 111 may be allocated to the first sensor node A 101, and a time slot (7) 113 may be allocated to the third sensor node C 105. Therefore, the first sensor node A 101 may transmit a beacon and data in the allocated time slot (1) 111. Neighboring nodes may simplify receive the beacon and the data in the time slot (1) 111.
In the above mesh network, each sensor node may need to be awakened every time slot of all the neighboring nodes. For example, when the first sensor node A 101 broadcasts a beacon 131 in the allocated time slot (1) 111, neighboring nodes of the first sensor node A 101, that is, the second sensor node B 103, the third sensor node C 105, and the fourth sensor node 1) 107 may be awakened in the time slot (1) 111 and receive beacons 133, 135, and 137, respectively, and may prepare to receive data of the first sensor node A 101.
Accordingly, there is a need for a sensor node of a low power for a monitoring application that may be awakened only in a time slot of a necessary neighboring node to thereby decrease a power consumption in a mesh sensor network using a time division access scheme, and a routing method thereof.